The emergence of light systems based on laser diodes in the area of motor vehicles requires increasingly higher modulation speeds of the diode current, wherein for this modulation, a high-frequency closed-loop or open-loop control must be provided. Conventional DC/DC converters used for LED control are no longer usable at modulation frequencies in the MHz range, and so for applications at such high switching frequencies, a particularly fast closed-loop or open-loop current control must be provided. A possible design is an upstream “slow” DC/DC converter (e.g. boost) with a subsequent analog linear stage. However, such a downstream linear stage results in irregular stress on the DC/DC converter and to a permanent power loss.
Document EP 2 670 218 A1 describes a control for LEDs of a headlight; however, it is not a scanning system of the type in question, in which a modulated laser beam is directed by means of a light scanner to a light conversion means in order to create a luminous image on same which is projected as light image onto the road.
Document AT 513 916 A2 shows a headlight on the basis of a modulated laser light source with a scanning laser beam for generating a luminous image on a light conversion means, wherein the control of a plurality of lasers is only described in general without elaborating on circuit details.
For a vehicle headlight according to the preamble of the independent claim, the current in the light source branch must be adjusted due to the continuous adjustment to the required light image, wherein operation takes place mainly in the range of the maximum current, which results in considerable losses.
A problem addressed by the invention is that of creating a headlight which uses a laser beam generated, modulated and scanning by laser diodes, and in which no high losses occur which not only result in an increased thermal stress but also in high costs due to the required dimensioning. Particularly the voltage supply of the laser diode(s), for example, a DC/DC converter, is supposed to be stressed as evenly as possible, regardless of the modulation processes.